The present invention relates to a fine particle dispersant as well as cosmetics, paints, inks, memorizing materials and lubricants containing the dispersant.
Techniques for dispersing fine particles are now employed in various fields of cosmetics, paints, inks, memorizing materials, lubricants, medicines, foods, etc. Main factors for determining the fine particle-dispersing function are, for example, characteristics of the fine particles such as pigments and also characteristics of vehicles such as resins, solvents and additives. Particularly for the latter, various ideas were proposed for improving the fine particle-dispersing function in various fields.
In the field of cosmetics, for example, castor oil has so far been used as base oil for a lipstick for dispersing a pigment. Because ricinoleic acid which is a typical hydroxyl acid is a main fatty acid component of castor oil, this oil has a polarity higher than that of other vegetable oils, hydrophilic property, humectant effect and a high viscosity. Taking advantage of these properties, ricinoleic acid has been used as a medium in kneading a pigment from old times. Castor oil is usually used in an amount of 20 to 50% based on a liquid oil in the base. If castor oil is used in an excessive amount, problems such as an odor of the castor oil and deterioration of feeling upon use thereof with time are posed. In addition, because castor oil has a high polarity, the compatibility thereof with a starting hydrocarbon is low and, therefor, the use of an ester oil as a binder is indispensable. Another problem of castor oil is that it is irritating.
Japanese Patent Examined Publication (hereinafter referred to as “J. P. KOKOKU”) No. Sho 53-46890/1978 discloses cosmetics containing a full ester compound of trimethylolpropane. It is described therein that basic cosmetics, makeup cosmetics, hair cosmetics, etc. having an excellent feel to the touch to the skin and also excellent storability can be provided. Japanese Patent Unexamined Published Application (hereinafter referred to as “J. P. KOKAI”) Nos. 247844/2001 and 247845/2001 disclose a gelling agent comprising an esterification product obtained by the esterification reaction of trimethylolpropane or its condensate, a glycerol condensate, a long-chain, linear saturated basic acid having 6 to 30 carbon atoms and a fatty acid having 8 to 28 carbon atoms.
However, those specifications are silent about a fine particle dispersant having an excellent fine particle-dispersibility and only a slight deterioration of the properties (odor and color) in heat stability tests.